Semiconductor device and method of fabrication

Abstract

A MEMS (micro electro-mechanical system) semiconductor device and a method for producing such a device. A preferred embodiment of the present invention comprises the a wafer having a continuous BCS (bondline control structure) surrounding a MEMS active area that is affixed to an interposer layer, which is in turn affixed to a cover to form a sealed cavity over the surface of the MEMS. To fabricate this device, a wafer is populated with MEMS devices. The BCS is formed in the same process step as a device structure, for example a spacer layer. The BCS remains, however, even if all or a portion of this spacer layer is removed. In this way when the reflecting surface of the MEMS device has been formed, an interposer layer may be mounted to the BCS using a filler-less adhesive, and a cover can likewise be affixed to the interposer layer.

1. A method for fabricating a micro-electromechanical system (MEMS) device, comprising:
 forming at least one active area on a substrate; 
 forming a bondline control structure (BCS) on the substrate peripheral to the at least one active area; and 
 mounting a cover on the BCS to form a closed recess between the cover and the active area. 
 
   
   
     2. The method of  claim 1 , wherein mounting the cover comprises:
 mounting an interposer to the BCS; and 
 mounting a cover plate to the interposer. 
 
   
   
     3. The method of  claim 1 , wherein mounting the cover further comprises applying an adhesive. 
   
   
     4. The method of  claim 3 , wherein the adhesive is applied to a portion of the cover. 
   
   
     5. The method of  claim 3 , wherein the adhesive is applied to at least a portion of the BCS. 
   
   
     6. The method of  claim 1 , wherein the cover is made of a clear glass material. 
   
   
     7. The method of  claim 1 , wherein the BCS is formed in process. 
   
   
     8. The method of  claim 1 , wherein the BCS forms a raised structure continuous about the active area interposer. 
   
   
     9. The method of  claim 1 , wherein the at least one active area comprises a plurality of active areas, and further comprising the step of singulating the covered substrate. 
   
   
     10. An electro-mechanical device, comprising:
 an active area formed on a substrate; 
 at least one BCS formed on the substrate peripheral to the active area; and 
 a cover mounted on the BCS. 
 
   
   
     11. The electro-mechanical device of  claim 10 , wherein the substrate is a semiconductor wafer. 
   
   
     12. The electro-mechanical device of  claim 10 , wherein the active area substantially forms the reflecting surface of a MEMS device. 
   
   
     13. The electro-mechanical device of  claim 12 , wherein the MEMS device is a digital micro-mirror device (DMD). 
   
   
     14. The electro-mechanical device of  claim 10 , wherein the at least one peripheral BCS is continuous about the active area. 
   
   
     15. The electro-mechanical device of  claim 10 , wherein the at least one peripheral BCS comprises at least a second peripheral BCS. 
   
   
     16. The electro-mechanical device of  claim 10 , further comprising a plurality of BCSs disposed outside of the at least one peripheral BCS. 
   
   
     17. The electro-mechanical device of  claim 10 , wherein the cover comprises an interposer for mounting to the at least one peripheral BCS. 
   
   
     18. The electro-mechanical device of  claim 10 , wherein the cover further comprises a cover wafer mounted to the interposer. 
   
   
     19. The electro-mechanical device of  claim 10 , wherein the at least one peripheral BCS is formed in-process.